Heat pump use apparatus

ABSTRACT

Provided is a heat pump use apparatus, including a refrigerant circuit, a heat medium circuit, and a heat exchanger configured to exchange heat between refrigerant and a heat medium. A main passage of the heat medium circuit includes a branching portion and a joining portion. A pressure protection device and a refrigerant leakage detection device are connected to the main passage. The pressure protection device is connected to the main passage at a connecting portion located between the heat exchanger and one of the branching portion and the joining portion. A first interruption device configured to be able to interrupt a flow from the heat exchanger to the connecting portion is provided in the main passage at a portion between the heat exchanger and the connecting portion. A second interruption device configured to be able to interrupt a flow from the heat exchanger to an other of the branching portion and the joining portion is provided in the main passage at a portion between the heat exchanger and the other of the branching portion and the joining portion.

TECHNICAL FIELD

The present invention relates to a heat pump use apparatus including arefrigerant circuit and a heat medium circuit.

BACKGROUND ART

In Patent Literature 1, there is described an outdoor unit for a heatpump cycle apparatus using flammable refrigerant. The outdoor unitincludes a refrigerant circuit including a compressor, an air heatexchanger, an expansion device, and a water heat exchanger, which areconnected to one another through pipes, and a pressure relief valveconfigured to prevent excessive rise of water pressure in a watercircuit configured to supply water heated in the water heat exchanger.With this configuration, even when a partition wall configured topartition the refrigerant circuit and the water circuit is broken in thewater heat exchanger so that the flammable refrigerant is mixed into thewater circuit, the flammable refrigerant can be discharged to theoutside through the pressure relief valve.

CITATION LIST Patent Literature

Patent Literature 1: Japanese Unexamined Patent Application PublicationNo. 2013-167398

SUMMARY OF INVENTION Technical Problem

In a heat pump use apparatus such as the heat pump cycle apparatus, ingeneral, a pressure relief valve of the water circuit is provided in anindoor unit. There are various combinations of the outdoor unit and theindoor unit in the heat pump use apparatus. An outdoor unit and anindoor unit, which are manufactured by the same manufacturer, may becombined. Further, an outdoor unit and an indoor unit, which aremanufactured by different manufacturers, may be combined. Therefore, theoutdoor unit described in Patent Literature 1 may be combined with theindoor unit including the pressure relief valve.

However, in Patent Literature 1, when the refrigerant is leaked to thewater circuit, the refrigerant mixed into water inside the water circuitmay be discharged not only through the pressure relief valve provided inthe outdoor unit, but also through the pressure relief valve provided inthe indoor unit. Therefore, there is a problem in that the refrigerantmay be leaked to a room through the water circuit.

The present invention has been made to solve the problem describedabove, and has an object to provide a heat pump use apparatus capable ofpreventing leakage of refrigerant to a room.

Solution to Problem

According to one embodiment of the present invention, there is provideda heat pump use apparatus, including: a refrigerant circuit configuredto circulate refrigerant; a heat medium circuit configured to allow aheat medium to flow therethrough; and a heat exchanger configured toexchange heat between the refrigerant and the heat medium. The heatmedium circuit includes a main passage extending through the heatexchanger. The main passage includes: a branching portion to which aplurality of branch passages branched from the main passage areconnected, the branching portion being provided at a downstream end ofthe main passage; and a joining portion at which the plurality of branchpassages are connected to each other to be joined to the main passage,the joining portion being provided at an upstream end of the mainpassage. The heat pump use apparatus further includes a pressureprotection device and a refrigerant leakage detection device that areconnected to the main passage. The pressure protection device isconnected to the main passage at a connecting portion located betweenthe heat exchanger and one of the branching portion and the joiningportion. The main passage includes a first interruption deviceconfigured to be able to interrupt a flow from the heat exchanger to theconnecting portion. The first interruption device is provided betweenthe heat exchanger and the connecting portion. The main passage includesa second interruption device configured to be able to interrupt a flowfrom the heat exchanger to an other of the branching portion and thejoining portion, The second interruption device is provided between theheat exchanger and the other of the branching portion and the joiningportion.

Advantageous Effects of Invention

According to one embodiment of the present invention, even when therefrigerant is leaked to the heat medium circuit, a flow of therefrigerant mixed into the heat medium can be interrupted by theinterruption device. Therefore, the leakage of the refrigerant from thepressure protection device to the room can be prevented.

BRIEF DESCRIPTION OF DRAWINGS

[FIG. 1] FIG. 1 is a circuit diagram for illustrating a schematicconfiguration of a heat pump use apparatus according to Embodiment 1 ofthe present invention.

[FIG. 2] FIG. 2 is a circuit diagram for illustrating a schematicconfiguration of a heat pump use apparatus of a modification example ofEmbodiment 1 of the present invention.

[FIG. 3] FIG. 3 is an explanatory view for illustrating examples of anarrangement position of a refrigerant leakage detection device 98 in theheat pump use apparatus according to Embodiment 1 of the presentinvention.

[FIG. 4] FIG. 4 is an explanatory view for illustrating the example ofthe arrangement position of the refrigerant leakage detection device 98in the heat pump use apparatus according to Embodiment 1 of the presentinvention.

[FIG. 5] FIG. 5 is an explanatory view for illustrating the example ofthe arrangement position of the refrigerant leakage detection device 98in the heat pump use apparatus according to Embodiment 1 of the presentinvention.

[FIG. 6] FIG. 6 is an explanatory view for illustrating the example ofthe arrangement position of the refrigerant leakage detection device 98in the heat pump use apparatus according to Embodiment 1 of the presentinvention.

[FIG. 7] FIG. 7 is a circuit diagram for illustrating a schematicconfiguration of a heat pump use apparatus according to Embodiment 2 ofthe present invention.

DESCRIPTION OF EMBODIMENTS Embodiment 1

A heat pump use apparatus according to Embodiment 1 of the presentinvention is described. FIG. 1 is a circuit diagram for illustrating aschematic configuration of the heat pump use apparatus according toEmbodiment 1. In Embodiment 1, a heat pump water heater 1000 isexemplified as the heat pump use apparatus. In the drawings includingFIG. 1 referred to below, a dimensional relationship of components and ashape of each of the components may be different from those of actualcomponents.

As illustrated in FIG. 1, the heat pump water heater 1000 includes arefrigerant circuit 110 configured to circulate refrigerant and a watercircuit 210 configured to allow water to flow therethrough. Further, theheat pump water heater 1000 includes an outdoor unit 100 installedoutside, for example, outdoor space, and an indoor unit 200 installedindoor space. The indoor unit 200 is installed, for example, in akitchen, a bathroom, or a laundry room or, further, in a storage spacesuch as a closet inside a building.

The refrigerant circuit 110 includes a compressor 3, a refrigerant flowswitching device 4, a load-side heat exchanger 2, a first pressurereducing device 6, an intermediate pressure receiver 5, a secondpressure reducing device 7, and a heat source-side heat exchanger 1,which are annularly connected in order through refrigerant pipes.Through use of the refrigerant circuit 110, the heat pump water heater1000 is capable of a normal operation, for example, heater water heatingoperation, for heating water flowing through the water circuit 210 and adefrosting operation for circulating the refrigerant reversely to thenormal operation to defrost the heat source-side heat exchanger 1.

The compressor 3 is a fluid machine configured to compress suckedlow-pressure refrigerant and to discharge the low-pressure refrigerantas high-pressure refrigerant. The compressor 3 of Embodiment 1 includesan inverter device, and is configured to change a driving frequencyfreely selectively, to thereby be able to change a capacity, that is, anamount of the refrigerant to be sent per unit time.

The refrigerant flow switching device 4 is configured to switch a flowdirection of the refrigerant inside the refrigerant circuit 110 betweenthe normal operation and the defrosting operation. As the refrigerantflow switching device 4, for example, a four-way valve is used.

The load-side heat exchanger 2 is a water-refrigerant heat exchangerconfigured to exchange heat between the refrigerant flowing through therefrigerant circuit 110 and the water flowing through the water circuit210. As the load-side heat exchanger 2, for example, a plate heatexchanger is used. The load-side heat exchanger 2 includes a refrigerantflow passage for allowing refrigerant to flow therethrough as a part ofthe refrigerant circuit 110, a water flow passage for allowing water toflow therethrough as a part of the water circuit 210, and a thinplate-like partition wall configured to partition the refrigerant flowpassage and the water flow passage. The load-side heat exchanger 2functions as a condenser (radiator) configured to heat water during thenormal operation, and functions as an evaporator (heat absorber) duringthe defrosting operation.

The first pressure reducing device 6 is configured to regulate a flowrate of refrigerant, for example, regulate a pressure of the refrigerantflowing into the load-side heat exchanger 2. The intermediate pressurereceiver 5 is located between the first pressure reducing device 6 andthe second pressure reducing device 7 in the refrigerant circuit 110,and is configured to accumulate an excess of the refrigerant. A suctionpipe 11 connected to a suction side of the compressor 3 passes throughthe inside of the intermediate pressure receiver 5. In the intermediatepressure receiver 5, heat is exchanged between the refrigerant passingthrough the suction pipe 11 and the refrigerant inside the intermediatepressure receiver 5. Therefore, the intermediate pressure receiver 5 hasa function as an internal heat exchanger for the refrigerant circuit110. The second pressure reducing device 7 is configured to regulate thepressure of the refrigerant by regulating the flow rate of therefrigerant. The first pressure reducing device 6 and the secondpressure reducing device 7 of Embodiment 1 are each an electronicexpansion valve capable of changing an opening degree based on aninstruction from a controller 101 described later.

The heat source-side heat exchanger 1 is an air-refrigerant heatexchanger configured to exchange heat between the refrigerant flowingthrough the refrigerant circuit 110 and outdoor air sent by an outdoorair-sending fan or other devices (not shown). The heat source-side heatexchanger 1 functions as an evaporator (heat absorber) during the normaloperation, and functions as a condenser (radiator) during the defrostingoperation.

Examples of refrigerants used as the refrigerants to be circulatedthrough the refrigerant circuit 110 include a slightly flammablerefrigerant such as R1234yf or R1234ze(E) and a strongly flammablerefrigerant such as R290 or R1270. Those refrigerants may be each usedas a single refrigerant, or may be used as a mixed refrigerant obtainedby mixing two or more kinds of the refrigerants with each other. In thefollowing description, the refrigerant having flammability equal to orhigher than a slightly flammable level (for example, 2L or higher incategory of ASHRAE34) may be referred to as “refrigerant havingflammability” or “flammable refrigerant”. Further, as the refrigerant tobe circulated through the refrigerant circuit 110, a nonflammablerefrigerant such as R4070 or R410A having nonflammability (for example,1 in the category of ASHRAE34) can be used. Those refrigerants have adensity larger than that of air under an atmospheric pressure (forexample, with a temperature being a room temperature (25 degreesCelsius)). Further, as the refrigerant to be circulated through therefrigerant circuit 110, a refrigerant having toxicity such as R717(ammonia) may also be used.

The outdoor unit 100 accommodates the refrigerant circuit 110 includingthe compressor 3, the refrigerant flow switching device 4, the load-sideheat exchanger 2, the first pressure reducing device 6, the intermediatepressure receiver 5, the second pressure reducing device 7, and the heatsource-side heat exchanger 1.

Further, the outdoor unit 100 includes the controller 101 configured tomainly control an operation of the refrigerant circuit 110, for example,the compressor 3, the refrigerant flow switching device 4, the firstpressure reducing device 6, the second pressure reducing device 7, andthe outdoor air-sending fan (not shown). The controller 101 includes amicrocomputer including a CPU, a ROM, a RAM, and an I/O port. Thecontroller 101 can communicate with a controller 201 and an operationunit 202, which are described later, through a control line 102.

Next, an example of the operation of the refrigerant circuit 110 isdescribed. In FIG. 1, the flow direction of the refrigerant in therefrigerant circuit 110 during the normal operation is indicated bysolid arrows. The refrigerant circuit 110 is configured so that, duringthe normal operation, the refrigerant flow passage is switched by therefrigerant flow switching device 4 as indicated by the solid arrows tocause the high-temperature and high-pressure refrigerant to flow intothe load-side heat exchanger 2.

The high-temperature and high-pressure gas refrigerant discharged fromthe compressor 3 passes through the refrigerant flow switching device 4,and flows into the refrigerant flow passage of the load-side heatexchanger 2. During the normal operation, the load-side heat exchanger 2functions as a condenser. That is, in the load-side heat exchanger 2,heat is exchanged between the refrigerant flowing through therefrigerant flow passage and the water flowing through the water flowpassage of the load-side heat exchanger 2, and the heat of condensationof the refrigerant is transferred to the water. With this operation, therefrigerant flowing through the refrigerant flow passage of theload-side heat exchanger 2 is condensed to become a high-pressure liquidrefrigerant. Further, the water flowing through the water flow passageof the load-side heat exchanger 2 is heated by transfer heat from therefrigerant.

The high-pressure liquid refrigerant condensed by the load-side heatexchanger 2 flows into the first pressure reducing device 6, and has thepressure reduced slightly to become a two-phase refrigerant. Thetwo-phase refrigerant flows into the intermediate pressure receiver 5,and is cooled by the heat exchange with a low-pressure gas refrigerantflowing through the suction pipe 11 to become a liquid refrigerant. Theliquid refrigerant flows into the second pressure reducing device 7, andhas the pressure reduced to become a low-pressure two-phase refrigerant.The low-pressure two-phase refrigerant flows into the heat source-sideheat exchanger 1. During the normal operation, the heat source-side heatexchanger 1 functions as an evaporator. That is, in the heat source-sideheat exchanger 1, heat is exchanged between the refrigerant circulatedthrough the inside and the outdoor air sent by the outdoor air-sendingfan, and the heat of evaporation of the refrigerant is received from theoutdoor air. With this operation, the refrigerant that has flowed intothe heat source-side heat exchanger 1 evaporates to become thelow-pressure gas refrigerant. The low-pressure gas refrigerant passesthrough the refrigerant flow switching device 4, and flows into thesuction pipe 11. The low-pressure gas refrigerant that has flowed intothe suction pipe 11 is heated by the heat exchange with the refrigerantinside the intermediate pressure receiver 5, and is sucked by thecompressor 3. The refrigerant sucked by the compressor 3 is compressedto become the high-temperature and high-pressure gas refrigerant. In thenormal operation, the above-mentioned cycle is repeated.

Next, an example of the operation during the defrosting operation isdescribed. In FIG. 1, the flow direction of the refrigerant in therefrigerant circuit 110 during the defrosting operation is indicated bythe broken arrows. The refrigerant circuit 110 is configured so that,during the defrosting operation, the refrigerant flow passage isswitched by the refrigerant flow switching device 4 as indicated by thebroken arrows to cause the high-temperature and high-pressurerefrigerant to flow into the heat source-side heat exchanger 1.

The high-temperature and high-pressure gas refrigerant discharged fromthe compressor 3 passes through the refrigerant flow switching device 4,and flows into the heat source-side heat exchanger 1. During thedefrosting operation, the heat source-side heat exchanger 1 functions asa condenser. That is, in the heat source-side heat exchanger 1, the heatof condensation of the refrigerant circulated through the inside istransferred to frost adhering to a surface of the heat source-side heatexchanger 1. With this operation, the refrigerant circulated through theinside of the heat source-side heat exchanger 1 is condensed to becomethe high-pressure liquid refrigerant. Further, the frost adhering to thesurface of the heat source-side heat exchanger 1 is melted by transferheat from the refrigerant.

The high-pressure liquid refrigerant condensed by the heat source-sideheat exchanger 1 passes through the second pressure reducing device 7,the intermediate pressure receiver 5, and the first pressure reducingdevice 6 to become the low-pressure two-phase refrigerant, and flowsinto the refrigerant flow passage of the load-side heat exchanger 2. Theload-side heat exchanger 2 functions as an evaporator during thedefrosting operation. That is, in the load-side heat exchanger 2, heatis exchanged between the refrigerant flowing through the refrigerantflow passage and the water flowing through the water flow passage, andheat of evaporation of the refrigerant is received from the water. Withthis operation, the refrigerant flowing through the refrigerant flowpassage of the load-side heat exchanger 2 evaporates to become thelow-pressure gas refrigerant. The gas refrigerant passes through therefrigerant flow switching device 4 and the suction pipe 11, and issucked by the compressor 3. The refrigerant sucked by the compressor 3is compressed to become the high-temperature and high-pressure gasrefrigerant. In the defrosting operation, the above-mentioned cycle iscontinuously repeated.

Next, the water circuit 210 is described. The water circuit 210 ofEmbodiment 1 is a closed circuit configured to circulate water. In FIG.1, the flow direction of the water is indicated by outline arrows, Thewater circuit 210 is constructed by a water circuit on the outdoor unit100 side and a water circuit on the indoor unit 200 side, which areconnected to each other. The water circuit 210 includes a main passage220, a branch passage 221 constructing a hot water circuit, and a branchpassage 222 constructing a part of a heater circuit. The main passage220 constructs a part of the closed circuit. The branch passages 221 and222 are each connected to the main passage 220 so as to be branched fromthe main passage 220. The branch passages 221 and 222 are provided inparallel to each other. The branch passage 221 constructs the closedcircuit together with the main passage 220. The branch passage 222constructs the closed circuit together with the main passage 220, aheater 300 connected to the branch passage 222, and other units. Theheater 300 is provided indoor space separately from the indoor unit 200.As the heater 300, a radiator or a floor heater is used, for example.

In Embodiment 1, water is taken as an example of a heat mediumcirculated through the water circuit 210. However, as the heat medium,other liquid heat media such as brine may be used.

The main passage 220 includes a strainer 56, a flow switch 57, theload-side heat exchanger 2, a booster heater 54, and a pump 53, whichare connected to one another through water pipes. A drain outlet 62configured to drain water inside the water circuit 210 is formed in ahalfway part of the water pipes that construct the water circuit 210. Adownstream end of the main passage 220 is connected to an inflow port ofa three-way valve 55 (example of a branching portion) having one inflowport and two outflow ports. At the three-way valve 55, the branchpassages 221 and 222 are branched from the main passage 220. An upstreamend of the main passage 220 is connected to a joining portion 230. Atthe joining portion 230, the branch passages 221 and 222 are joined tothe main passage 220. The water circuit 210 extending from the joiningportion 230 to the three-way valve 55 through the load-side heatexchanger 2 and other units corresponds to the main passage 220.

The load-side heat exchanger 2 of the main passage 220 is provided inthe outdoor unit 100. Of the units of the main passage 220, units otherthan the load-side heat exchanger 2 are provided in the indoor unit 200.That is, the main passage 220 of the water circuit 210 is providedacross the outdoor unit 100 and the indoor unit 200. A part of the mainpassage 220 is provided in the outdoor unit 100, and an other part ofthe main passage 220 is provided in the indoor unit 200. The outdoorunit 100 and the indoor unit 200 are connected to each other through twoconnecting pipes 211 and 212 constructing parts of the main passage 220.

The pump 53 is a device configured to apply pressure to the water insidethe water circuit 210 to circulate the water through the inside of thewater circuit 210. The booster heater 54 is a device configured tofurther heat the water inside the water circuit 210 when, for example,the outdoor unit 100 has insufficient heating capacity. The three-wayvalve 55 is a device configured to switch a flow of the water inside thewater circuit 210. For example, the three-way valve 55 switches adestination to which the water inside the main passage 220 is to becirculated between the branch passage 221 side and the branch passage222 side. The strainer 56 is a device configured to remove scale insidethe water circuit 210. The flow switch 57 is a device configured todetect whether or not the flow rate of the water circulated through theinside of the water circuit 210 is equal to or larger than a fixedamount. A flow rate sensor may also be used instead of the flow switch57.

A pressure relief valve 70 (example of a pressure protection device) isconnected to the booster heater 54. That is, the booster heater 54serves as a connecting portion for the pressure relief valve 70 (exampleof the pressure protection device). In the following, the connectingportion for the pressure relief valve 70 may be simply expressed as the“connecting portion”. The pressure relief valve 70 is a protectiondevice configured to prevent excessive rise of the pressure in the watercircuit 210, which is caused by temperature change of water. Thepressure relief valve 70 is configured to release water to the outsideof the water circuit 210 based on pressure in the water circuit 210. Forexample, when the pressure in the water circuit 210 is increased toexceed a pressure control range of an expansion tank 52 described later,the pressure relief valve 70 is opened, and the water inside the watercircuit 210 is released to the outside through the pressure relief valve70. The pressure relief valve 70 is provided in the indoor unit 200. Thepressure relief valve 70 is provided in the indoor unit 200 so as toprotect the pressure in the water circuit 210 in the indoor unit 200.

One end of a pipe 72, which is a water flow passage branched from themain passage 220, is connected to a casing of the booster heater 54. Thepressure relief valve 70 is mounted to an other end of the pipe 72. Thatis, the pressure relief valve 70 is connected to the booster heater 54through the pipe 72. The booster heater 54 serves as the connectingportion for connecting the pressure relief valve 70 to the main passage220. In the main passage 220, a water temperature becomes the highest inthe booster heater 54. Therefore, the booster heater 54 is optimum asthe connecting portion for connecting the pressure relief valve 70.Further, when the pressure relief valve 70 is connected to the branchpassages 221 and 222, the pressure relief valve 70 needs to be providedfor each of the branch passages 221 and 222. In Embodiment 1, thepressure relief valve 70 is connected to the main passage 220.Therefore, it is only necessary to provide one pressure relief valve 70.

A branching portion 72 a is provided on a halfway part of the pipe 72.One end of a pipe 75 is connected to the branching portion 72 a. Theexpansion tank 52 is connected to an other end of the pipe 75. That is,the expansion tank 52 is connected to the booster heater 54 through thepipes 75 and 72. The expansion tank 52 is a device configured to controlthe pressure change inside the water circuit 210, which is caused bytemperature change of water, within a predetermined range.

An interruption device 77 is provided downstream of the load-side heatexchanger 2 as a first interruption device. The interruption device 77is provided in the main passage 220 at a portion between the load-sideheat exchanger 2 and the booster heater 54, that is, the connectingportion for connecting the pressure relief valve 70. As the interruptiondevice 77, there may be used an on-off valve such as a solenoid valve, aflow control valve, or an electronic expansion valve. The interruptiondevice 77 is in a closed state during the normal operation. When theinterruption device 77 is in the closed state, the interruption device77 interrupts a flow from the load-side heat exchanger 2 toward thebooster heater 54. The interruption device 77 is controlled by thecontroller 201 described later. When the connecting portion forconnecting the pressure relief valve 70 is provided between theload-side heat exchanger 2 and the joining portion 230, the interruptiondevice 77 is provided as a second interruption device in the mainpassage 220 at a portion between the load-side heat exchanger 2 and thethree-way valve 55 (branching portion).

An interruption device 78 is provided upstream of the load-side heatexchanger 2 as the second interruption device. The interruption device78 is provided in the main passage 220 at a portion between theload-side heat exchanger 2 and the joining portion 230. As theinterruption device 78, there may be used a check valve configured toallow a flow of water from the joining portion 230 to the load-side heatexchanger 2, and to interrupt a flow from the load-side heat exchanger 2to the joining portion 230. Further, as the interruption device 78,there may also be used an on-off valve such as a solenoid valve, a flowcontrol valve, or an electronic expansion valve. When the on-off valveis used as the interruption device 78, the interruption device 78 iscontrolled by the controller 201 described later, or is operated inassociation with the interruption device 77. When the connecting portionfor connecting the pressure relief valve 70 is provided between theload-side heat exchanger 2 and the joining portion 230, the interruptiondevice 78 is provided as the first interruption device in the mainpassage 220 at a portion between the load-side heat exchanger 2 and theconnecting portion.

A refrigerant leakage detection device 98 is provided downstream of theinterruption device 77. The refrigerant leakage detection device 98 isconnected to the main passage 220 at a portion between the interruptiondevice 77 and the booster heater 54 (connecting portion). Therefrigerant leakage detection device 98 is a device configured to detectleakage of refrigerant from the refrigerant circuit 110 to the watercircuit 210. When the refrigerant is leaked from the refrigerant circuit110 to the water circuit 210, the pressure in the water circuit 210rises. Therefore, the refrigerant leakage detection device 98 is capableof detecting the leakage of the refrigerant into the water circuit 210based on the pressure in the water circuit 210, that is, a value of thepressure or temporal change of the pressure. As the refrigerant leakagedetection device 98, for example, a pressure sensor or a pressure switch(high-pressure switch) configured to detect the pressure in the watercircuit 210 is used. For example, the pressure switch may be an electricpressure switch or a mechanical pressure switch using a diaphragm. Therefrigerant leakage detection device 98 is configured to output adetection signal to the controller 201.

In Embodiment 1, both of the interruption devices 77 and 78 and therefrigerant leakage detection device 98 are provided in the indoor unit200. With this configuration, each of the interruption devices 77 and 78and the refrigerant leakage detection device 98 can be connected to thecontroller 201 through a control line in the indoor unit 200. Thus,costs can be reduced. All of the interruption devices 77 and 78 and therefrigerant leakage detection device 98 may be provided in the outdoorunit 100. With this configuration, each of the interruption devices 77and 78 and the refrigerant leakage detection device 98 can be connectedto the controller 101 through a control line in the outdoor unit 100.Thus, costs can be reduced.

The branch passage 221 constructing the hot water circuit is provided inthe indoor unit 200. An upstream end of the branch passage 221 isconnected to one outflow port of the three-way valve 55. A downstreamend of the branch passage 221 is connected to the joining portion 230. Acoil 61 is provided in the branch passage 221. The coil 61 is built in ahot-water storage tank 51 configured to store water therein. The coil 61is a heating unit configured to heat the water accumulated in thehot-water storage tank 51 through heat exchange with water (hot water)circulated through the branch passage 221 of the water circuit 210.Further, the hot-water storage tank 51 includes an immersion heater 60built therein. The immersion heater 60 is a heating unit configured tofurther heat the water accumulated in the hot-water storage tank 51.

A sanitary circuit-side pipe 81 a (for example, a hot water pipe), whichis to be connected to, for example, a shower, is connected to an upperportion inside the hot-water storage tank 51. A sanitary circuit-sidepipe 81 b (for example, a makeup water pipe) is connected to a lowerportion inside the hot-water storage tank 51. A drain outlet 63configured to drain water in the hot-water storage tank 51 is formed ina lower portion of the hot-water storage tank 51. In order to preventdecrease in temperature of the water inside the hot-water storage tank51 due to heat transfer to the outside, the hot-water storage tank 51 iscovered with a heat insulating material (not shown). Examples of theheat insulating material to be used include felt, Thinsulate(trademark), and a vacuum insulation panel (VIP).

The branch passage 222 constructing the part of the heater circuit isprovided in the indoor unit 200. The branch passage 222 includes asupply pipe 222 a and a return pipe 222 b. An upstream end of the supplypipe 222 a is connected to the other outflow port of the three-way valve55. A downstream end of the supply pipe 222 a and an upstream end of thereturn pipe 222 b are connected to heater circuit-side pipes 82 a and 82b, respectively. A downstream end of the return pipe 222 b is connectedto the joining portion 230. With this configuration, the supply pipe 222a and the return pipe 222 b are connected to the heater 300 through theheater circuit-side pipes 82 a and 82 b, respectively. The heatercircuit-side pipes 82 a and 82 b and the heater 300 are provided indoorspace but outside the indoor unit 200. The branch passage 222 constructsthe heater circuit together with the heater circuit-side pipes 82 a and82 b and the heater 300.

A pressure relief valve 301 is connected to the heater circuit-side pipe82 a. The pressure relief valve 301 is a protection device configured toprevent excessive rise of the pressure in the water circuit 210, and,for example, has the structure similar to that of the pressure reliefvalve 70. For example, when the pressure in the heater circuit-side pipe82 a is increased to exceed set pressure, the pressure relief valve 301is opened, and water in the heater circuit-side pipe 82 a is released tothe outside through the pressure relief valve 301. The pressure reliefvalve 301 is provided indoor space but outside the indoor unit 200.

The heater 300, the heater circuit-side pipes 82 a and 82 b, and thepressure relief valve 301 in Embodiment 1 are not parts of the heat pumpwater heater 1000, but units installed by an on-site installation workerdepending on circumstances of each building. For example, in an existingfacility using a boiler as a heat source device for the heater 300, theheat source device may be replaced by the heat pump water heater 1000.In such a case, unless it is inconvenient, the heater 300, the heatercircuit-side pipes 82 a and 82 b, and the pressure relief valve 301 areused as they are. Therefore, it is desired that the heat pump waterheater 1000 be able to be connected to various facilities irrespectiveof presence or absence of the pressure relief valve 301.

The indoor unit 200 includes the controller 201 configured to mainlycontrol an operation of the water circuit 210, for example, the pump 53,the booster heater 54, the three-way valve 55, and the interruptiondevice 77. The controller 201 includes a microcomputer including a CPU,a ROM, a RAM, and an I/O port. The controller 201 can communicate withthe controller 101 and the operation unit 202. The controller 201, forexample, sets the interruption device 77 to the closed state when thecontroller 201 detects the leakage of the refrigerant into the watercircuit 210 based on the detection signal from the refrigerant leakagedetection device 98. When the refrigerant leakage detection device 98 isconfigured to output a contact signal at the time of the leakage of therefrigerant, the refrigerant leakage detection device 98 may be directlyconnected to the interruption device 77 without connection through thecontroller 201.

The operation unit 202 allows a user to conduct the operation or varioussettings of the heat pump water heater 1000. The operation unit 202 ofEmbodiment 1 includes a display unit 203. The display unit 203 candisplay various kinds of information including a state of the heat pumpwater heater 1000. The operation unit 202 is provided, for example, on asurface of the casing of the indoor unit 200.

Next, description is made of an operation in a case where the partitionwall configured to partition the refrigerant flow passage and the waterflow passage in the load-side heat exchanger 2 is broken. The load-sideheat exchanger 2 functions as an evaporator during the defrostingoperation. Therefore, the partition wall of the load-side heat exchanger2 may be broken due to freezing of water or other causes particularlyduring the defrosting operation. In general, the pressure of therefrigerant flowing through the refrigerant flow passage of theload-side heat exchanger 2 is higher than the pressure of the waterflowing through the water flow passage of the load-side heat exchanger 2both during the normal operation and during the defrosting operation.Therefore, when the partition wall of the load-side heat exchanger 2 isbroken, the refrigerant in the refrigerant flow passage flows out to thewater flow passage both during the normal operation and during thedefrosting operation, and the refrigerant is mixed into the water insidethe water flow passage. At this time, the refrigerant mixed into thewater is gasified due to pressure decrease. Further, the refrigeranthaving the pressure higher than that of the water is mixed into thewater, with the result that the pressure in the water circuit 210 isincreased.

The refrigerant mixed into the water inside the water circuit 210 in theload-side heat exchanger 2 not only flows in a direction along a flow ofwater at a normal time, that is, a direction from the load-side heatexchanger 2 toward the booster heater 5, but, due to a pressuredifference, also flows in a direction opposite to the direction alongthe flow of water at the normal time, that is, a direction from theload-side heat exchanger 2 toward the joining portion 230. When thepressure relief valve 70 is provided in the main passage 220 of thewater circuit 210 as in Embodiment 1, the refrigerant mixed into thewater may be released from the pressure relief valve 70 to a roomtogether with the water. Further, when the pressure relief valve 301 isprovided in the heater circuit-side pipe 82 a or the heater circuit-sidepipe 82 b as in Embodiment 1, the refrigerant mixed into the water maybe released from the pressure relief valve 301 to the room together withthe water. That is, both of the pressure relief valves 70 and 301function as valves configured to release the refrigerant mixed into thewater inside the water circuit 210 to the outside of the water circuit210. When the refrigerant has flammability, there is a fear in that aflammable concentration region may be generated in the room due to therefrigerant released to the room.

However, in Embodiment 1, the interruption device 77 is provided betweenthe load-side heat exchanger 2 and the booster heater 54. Thus, a flowof the refrigerant from the load-side heat exchanger 2 to the boosterheater 54 can be interrupted. Therefore, leakage of the refrigerant fromthe pressure relief valve 70 to the room can be prevented. Further, inEmbodiment 1, the interruption device 78 is provided between theload-side heat exchanger 2 and the joining portion 230. Thus, a flow ofthe refrigerant from the load-side heat exchanger 2 to the joiningportion 230 can be interrupted. Therefore, leakage of the refrigerantfrom the pressure relief valve 301 to the room can be prevented.

FIG. 2 is a circuit diagram for illustrating a schematic configurationof a heat pump use apparatus of a modification example of Embodiment 1.As illustrated in FIG. 2, this modification example is different fromthe configuration illustrated in FIG. 1 in that the load-side heatexchanger 2 is accommodated in the indoor unit 200. The refrigerantcircuit 110 is provided across the outdoor unit 100 and the indoor unit200. A part of the refrigerant circuit 110 is provided in the outdoorunit 100, and an other part of the refrigerant circuit 110 is providedin the indoor unit 200. The outdoor unit 100 and the indoor unit 200 areconnected to each other through two connecting pipes 111 and 112constructing parts of the refrigerant circuit 110. Also according tothis modification example, effects similar to those of the configurationillustrated in FIG. 1 can be obtained. Further, in this modificationexample, all of the interruption devices 77 and 78 and the refrigerantleakage detection device 98 are provided in the indoor unit 200. Withthis configuration, each of the interruption devices 77 and 78 and therefrigerant leakage detection device 98 can be connected to thecontroller 201 through the control line in the indoor unit 200. Thus,costs can be reduced.

Next, an arrangement position of the refrigerant leakage detectiondevice 98 is described. FIG. 3 to FIG. 6 are explanatory views forillustrating examples of the arrangement position of the refrigerantleakage detection device 98 in the heat pump use apparatus according toEmbodiment 1. In FIG. 3, as the examples of the arrangement position ofthe refrigerant leakage detection device 98, four arrangement positionsA to D are illustrated. When the refrigerant leakage detection device 98is arranged at the arrangement position A or B, the refrigerant leakagedetection device 98 is connected to the pipe 72. That is, similarly tothe pressure relief valve 70, the refrigerant leakage detection device98 is connected to the main passage 220 at the booster heater 54(connecting portion). In such a case, before the refrigerant, which isleaked to the water circuit 210 at the load-side heat exchanger 2, isreleased from the pressure relief valve 70, the leakage of therefrigerant can reliably be detected by the refrigerant leakagedetection device 98. The similar effect is obtained also when therefrigerant leakage detection device 98 is connected to the main passage220 at the load-side heat exchanger 2, a portion between the load-sideheat exchanger 2 and the booster heater 54, or the booster heater 54.

Further, the refrigerant is gasified at a time point when therefrigerant is leaked to the water circuit 210. Therefore, due to adifference in specific volume between gas and a liquid, mass velocitywhen the refrigerant is leaked from the pressure relief valve 70 isreduced to about one thousandth of that when the liquid refrigerant isleaked. Therefore, an amount of the refrigerant, which may be releasedfrom the pressure relief valve 70 during a time period from detection ofthe leakage of the refrigerant to interruption of a flow at theinterruption device 77, does not reach an amount which leads togeneration of the flammable concentration region in the room.

Meanwhile, when the refrigerant leakage detection device 98 is arrangedat the arrangement position C or D, the refrigerant leakage detectiondevice 98 is connected to the main passage 220 at a portion between thebooster heater 54 (connecting portion) and the three-way valve 55. Inthis case, before the leakage of the refrigerant is detected by therefrigerant leakage detection device 98, the refrigerant may be releasedfrom the pressure relief valve 70. However, due to the difference inspecific volume between gas and a liquid as described above, the amountof the refrigerant that may be released from the pressure relief valve70 does not reach the amount which leads to the generation of theflammable concentration region in the room.

Further, as illustrated in FIG. 4, when the refrigerant leakagedetection device 98 is provided between the load-side heat exchanger 2and the interruption device 77, through the setting of the interruptiondevice 77 to the closed state immediately after the leakage of therefrigerant is detected, the amount of the refrigerant released from thepressure relief valve 70 can be reduced to almost exactly zero.Similarly, as illustrated in FIG. 5, when the refrigerant leakagedetection device 98 is provided between the load-side heat exchanger 2and the interruption device 78, an amount of the refrigerant releasedfrom the pressure relief valve 301 can be reduced to almost exactlyzero. That is, in order to reduce the amount of the refrigerant releasedto the room to almost exactly zero, it is desired that the refrigerantleakage detection device 98 be connected to the main passage 220 at aportion between the interruption device 77 and the interruption device78.

Further, as illustrated in FIG. 6, when the interruption device 78 isnot the check valve but the on-off valve, the refrigerant leakagedetection device 98 may be connected to the main passage 220 at aportion between the interruption device 78 and the joining portion 230.

In all of the configurations illustrated in FIG. 1 to FIG. 6, therefrigerant leakage detection device 98 is not connected to the branchpassage, for example, the heater circuit-side pipe 82 a or 82 b or theheater 300, which is installed by an on-site installation worker, but isconnected to the main passage 220. Therefore, mounting of therefrigerant leakage detection device 98 and connection between therefrigerant leakage detection device 98 and the controller 201 can becarried out by a manufacturer of the indoor unit 200. Therefore, it ispossible to avoid such a human error as to forget to mount therefrigerant leakage detection device 98 and connect the refrigerantleakage detection device 98.

As described above, the heat pump water heater 1000 (example of the heatpump use apparatus) according to Embodiment 1 includes the refrigerantcircuit 110 configured to circulate the refrigerant, the water circuit210 (example of the heat medium circuit) configured to allow water(example of the heat medium) to flow therethrough, and the load-sideheat exchanger 2 (example of the heat exchanger) configured to exchangeheat between the refrigerant and the water. The water circuit 210includes the main passage 220 extending through the load-side heatexchanger 2. The main passage 220 includes the three-way valve 55(example of the branching portion) to which the plurality of branchpassages 221 and 222 branched from the main passage 220 are connected,and the joining portion 230 at which the plurality of branch passages221 and 222 are connected to each other to be joined to the main passage220. The three-way valve 55 is provided at the downstream end of themain passage 220. The joining portion 230 is provided at the upstreamend of the main passage 220. The pressure relief valve 70 (example ofthe pressure protection device) and the refrigerant leakage detectiondevice 98 are connected to the main passage 220. The pressure reliefvalve 70 is configured to release water to the outside of the watercircuit 210 based on the pressure in the water circuit 210. Therefrigerant leakage detection device 98 is configured to detect theleakage of the refrigerant from the refrigerant circuit 110 to the watercircuit 210. The pressure relief valve 70 is connected to the mainpassage 220 at the booster heater 54 (example of the connecting portion)located between the load-side heat exchanger 2 and one of the three-wayvalve 55 and the joining portion 230. The interruption device 77(example of the first interruption device) configured to be able tointerrupt a flow from the load-side heat exchanger 2 to the boosterheater 54 is provided in the main passage 220 at a portion between theload-side heat exchanger 2 and the booster heater 54. The interruptiondevice 78 (example of the second interruption device) configured to beable to interrupt a flow from the load-side heat exchanger 2 to an otherof the three-way valve 55 and the joining portion 230 is provided in themain passage 220 at a portion between the load-side heat exchanger 2 andthe other of the three-way valve 55 and the joining portion 230.

According to this configuration, even when the refrigerant is leaked tothe water circuit 210 in the load-side heat exchanger 2, a flow of therefrigerant mixed into the water can be interrupted by the interruptiondevices 77 and 78. Therefore, the leakage of the refrigerant from thepressure relief valve 70 to the room can be prevented. Further, therecan also be prevented the leakage of the refrigerant to the room fromthe pressure relief valve 301 which may be provided to a circuitprovided ahead of the branching portion, for example, the heatercircuit-side pipes 82 a and 82 b.

In the heat pump water heater 1000 according to Embodiment 1, each ofthe interruption devices 77 and 78 is the on-off valve which is closedwhen the leakage of the refrigerant into the water circuit 210 isdetected. According to this configuration, when the refrigerant isleaked to the water circuit 210, the flow of the refrigerant mixed intothe water can further reliably be interrupted.

In the heat pump water heater 1000 according to Embodiment 1, therefrigerant leakage detection device 98 is connected to the main passage220 at the joining portion 230, a portion between the joining portion230 and the booster heater 54, or the booster heater 54. According tothis configuration, the leakage of the refrigerant can reliably bedetected before the refrigerant leaked to the water circuit 210 isreleased to the room.

In the heat pump water heater 1000 according to Embodiment 1, of theinterruption devices 77 and 78, the interruption device 78, which isprovided between the load-side heat exchanger 2 and the joining portion230, is the check valve. Further, the refrigerant leakage detectiondevice 98 is connected to the main passage 220 at a portion between thecheck valve and the booster heater 54 or at the booster heater 54,According to this configuration, the leakage of the refrigerant canreliably be detected before the refrigerant leaked to the water circuit210 is released to the room.

In the heat pump water heater 1000 according to Embodiment 1, therefrigerant leakage detection device 98 is connected to the main passage220 at a portion between the interruption device 77 and the interruptiondevice 78. According to this configuration, the amount of therefrigerant released from the pressure relief valve can be reduced toalmost exactly zero.

In the heat pump water heater 1000 according to Embodiment 1, therefrigerant leakage detection device 98 is configured to detect theleakage of the refrigerant into the water circuit 210 based on thepressure in the water circuit 210. According to this configuration, theleakage of the refrigerant can reliably be detected.

The heat pump water heater 1000 according to Embodiment 1 furtherincludes the outdoor unit 100 accommodating the refrigerant circuit 110,a part of the water circuit 210, and the load-side heat exchanger 2, andthe indoor unit 200 accommodating an other part of the water circuit210. One of the outdoor unit 100 and the indoor unit 200 accommodatesthe interruption devices 77 and 78 and the refrigerant leakage detectiondevice 98. According to this configuration, the controller 101 or thecontroller 201 can be connected to each of the interruption devices 77and 78 and the refrigerant leakage detection device 98 in the outdoorunit 100 or the indoor unit 200. Thus, costs can be reduced.

The heat pump water heater 1000 according to Embodiment 1 furtherincludes the outdoor unit 100 accommodating a part of the refrigerantcircuit 110, and the indoor unit 200 accommodating an other part of therefrigerant circuit 110, the water circuit 210, and the load-side heatexchanger 2. The indoor unit 200 accommodates the interruption devices77 and 78 and the refrigerant leakage detection device 98. According tothis configuration, the controller 201 can be connected to each of theinterruption devices 77 and 78 and the refrigerant leakage detectiondevice 98 in the indoor unit 200. Thus, costs can be reduced.

In the heat pump water heater 1000 according to Embodiment 1, therefrigerant may be flammable refrigerant or toxic refrigerant.

Embodiment 2

A heat pump use apparatus according to Embodiment 2 of the presentinvention is described. FIG. 7 is a circuit diagram for illustrating aschematic configuration of the heat pump use apparatus according toEmbodiment 2. In FIG. 7, a configuration of the indoor unit 200 ismainly illustrated. Components having the same functions and actions asthose of Embodiment 1 are denoted by the same reference symbols, anddescription thereof is omitted. As illustrated in FIG. 7, in Embodiment2, a boiler circuit 240 configured to heat water accumulated inside thehot-water storage tank 51 is provided outside the hot-water storage tank51. The boiler circuit 240 includes a water flow passage for connectinga lower portion and an upper portion of the hot-water storage tank 51.The boiler circuit 240 includes a boiler pump 241 and a boiler heatexchanger 242 configured to exchange heat between water flowing throughthe boiler circuit 240 and water flowing through the branch passage 221.When the boiler pump 241 is operated, water in the lower portion of thehot-water storage tank 51 flows into the boiler circuit 240. The waterflowing into the boiler circuit 240 is heated through heat exchange inthe boiler heat exchanger 242, and is returned to the upper portion ofthe hot-water storage tank 51. Also according to Embodiment 2, effectssimilar to those of Embodiment 1 can be obtained.

The present invention is not limited to the above-mentioned embodiments,and various modifications may be made thereto.

For example, in the above-mentioned embodiments, the plate heatexchanger is given as an example of the load-side heat exchanger 2.However, the load-side heat exchanger 2 may be a heat exchanger otherthan the plate heat exchanger, such as a double-pipe heat exchanger aslong as the heat exchanger is configured to exchange heat betweenrefrigerant and a heat medium.

Further, in the above-mentioned embodiments, the heat pump water heater1000 is given as an example of the heat pump use apparatus. However, thepresent invention is also applicable to other heat pump use apparatus,such as a chiller.

Further, in the above-mentioned embodiments, the indoor unit 200including the hot-water storage tank 51 is given as an example. However,the hot-water storage tank may be provided separately from the indoorunit 200.

The embodiments described above and the modification may be carried outin combinations.

REFERENCE SIGNS LIST

1 heat source-side heat exchanger 2 load-side heat exchanger 3compressor 4 refrigerant flow switching device 5 intermediate pressurereceiver

6 first pressure reducing device 7 second pressure reducing device 11suction pipe 51 hot-water storage tank 52 expansion tank 53 pump 54booster heater 55 three-way valve 56 strainer 57 flow switch 60immersion heater 61 coil 62, 63 drain outlet 70 pressure relief valve 72pipe 72 a branching portion 75 pipe 77, 78 interruption device 81 a, 81b sanitary circuit-side pipe 82 a, 82 b heater circuit-side pipe 98refrigerant leakage detection device 100 outdoor unit 101 controller 102control line

110 refrigerant circuit 111, 112 connecting pipe 200 indoor unit

201 controller 202 operation unit 203 display unit 210 water circuit 211212 connecting pipe 220 main passage 221, 222 branch passage 222 asupply pipe 222 b return pipe 230 joining portion 240 boiler circuit 241boiler pump 242 boiler heat exchanger 300 heater 301 pressure reliefvalve 1000 heat pump water heater

1. A heat pump use apparatus, comprising: a refrigerant circuitconfigured to circulate refrigerant; a heat medium circuit configured toallow a heat medium to flow therethrough; and a heat exchangerconfigured to exchange heat between the refrigerant and the heat medium,the heat medium circuit including a main passage extending through theheat exchanger, the main passage including a branching portion to whicha plurality of branch passages branched from the main passage areconnected, the branching portion being provided at a downstream end ofthe main passage, and a joining portion at which the plurality of branchpassages are connected to each other to be joined to the main passage,the joining portion being provided at an upstream end of the mainpassage, the heat pump use apparatus further comprising a pressureprotection device and a refrigerant leakage detection device that areconnected to the main passage, the pressure protection device beingconnected to the main passage at a connecting portion located betweenthe heat exchanger and one of the branching portion and the joiningportion, the main passage including a first interruption deviceconfigured to interrupt a flow from the heat exchanger to the connectingportion, the first interruption device being provided between the heatexchanger and the connecting portion, the main passage including asecond interruption device configured to interrupt a flow from the heatexchanger to an other of the branching portion and the joining portion,the second interruption device being provided between the heat exchangerand the other of the branching portion and the joining portion.
 2. Theheat pump use apparatus of claim 1, wherein each of the firstinterruption device and the second interruption device comprises anon-off valve which is closed when leakage of the refrigerant into theheat medium circuit is detected.
 3. The heat pump use apparatus of claim1, wherein the refrigerant leakage detection device is connected to themain passage at the other of the branching portion and the joiningportion, a portion between the other of the branching portion and thejoining portion and the connecting portion, or the connecting portion.4. The heat pump use apparatus of claim 1, wherein one interruptiondevice of the first interruption device and the second interruptiondevice, which is provided between the heat exchanger and the joiningportion, comprises a check valve, and wherein the refrigerant leakagedetection device is connected to the main passage at a portion betweenthe check valve and the connecting portion or at the connecting portion.5. The heat pump use apparatus of claim 1, wherein the refrigerantleakage detection device is connected to the main passage at a portionbetween the first interruption device and the second interruptiondevice.
 6. The heat pump use apparatus of claim 1, wherein therefrigerant leakage detection device is configured to detect the leakageof the refrigerant into the heat medium circuit based on pressure in theheat medium circuit.
 7. The heat pump use apparatus of claim 1, furthercomprising: an outdoor unit accommodating the refrigerant circuit, apart of the heat medium circuit, and the heat exchanger; and an indoorunit accommodating an other part of the heat medium circuit, wherein oneof the outdoor unit and the indoor unit accommodates the firstinterruption device, the second interruption device, and the refrigerantleakage detection device.
 8. The heat pump use apparatus of claim 1,further comprising: an outdoor unit accommodating a part of therefrigerant circuit; and an indoor unit accommodating an other part ofthe refrigerant circuit, the heat medium circuit, and the heatexchanger, wherein the indoor unit accommodates the first interruptiondevice, the second interruption device, and the refrigerant leakagedetection device.
 9. The heat pump use apparatus of claim 1, wherein therefrigerant comprises flammable refrigerant or toxic refrigerant.